Unloading device

ABSTRACT

A container unloading device which includes a two-tiered rail system that has been adapted to include an upper set of feed rails that cycle carts carrying containers from the back of the system to the front of the system for unloading. At the system&#39;s front end, the feed rails have sections of increased angularity which support the cart and container at an angle which increases accessibility to the container&#39;s contents. The system also includes a set of transfer ramps which allow the cart to move from rolling engagement with the feed rails to rolling engagement with the lower set of return rails where the cart and unloaded container then move to the back of the system into a position for reloading. The device may further include a speed reducer which retards the cart&#39;s acceleration down the sections of increased angularity.

BACKGROUND OF THE INVENTION

The present invention relates generally to unloading systems, and moreparticularly, to container unloading systems that selectively andautomatically cycle carts carrying unit loads, such as containers orparts bins, to the front of the system where the load is held at anangle for unloading and then cycles the carts and unloaded unitcontainers to the rear of the system for loading. Holding the containerand load at an angle increases the ease in which objects can be removedfrom the container which can lead to increases in productivity.

While this invention has applications in a wide range of industries, itis particularly useful to assembly line manufacturing. In this type ofoperation, an important consideration is supplying the line worker witha constant stream of parts. Another important consideration is ease ofaccess to the parts. Any delay in the parts stream or difficulties inobtaining parts can lead to inefficiencies of the entire assembly line.

While return systems, such as described in U.S. Pat. No. 5,170,896entitled "Pallet Return Pallet Rack System," can cycle carts carryingunit loads, these systems would not make suitable container unloadingsystems. First, these return systems do not increase access to thecontainer since they use gradually inclined rails and do not includesections of increased angularity. Second, without sections of increasedangularity, the height of the container and cart used is limited by thevertical distance between the systems' upper and lower rails. Since thisvertical distance is typically less than the height of a suitable partsbin or container, return systems, again, would not be practical ascontainer unloading devices.

Consequently, one of the advantages of a pallet return system is that itcan supply a steady stream of parts to the front of the system for useby the worker. However, in some applications, it may be necessary toprovide a way to improve the access to the parts by the worker and toprovide a system that could be used with suitable parts bins orcontainers.

SUMMARY OF THE INVENTION

The present invention preserves the advantages of the pallet returnsystem and also provides new features and advantages not found in theprior art. Specifically, the current invention provides a system thatcan support most types of containers at a selected angle duringunloading in order to improve the access to the parts inside of thecontainers. Once the container is emptied, it is then efficiently cycledto the rear of the system for reloading and another loaded container andcart moves forward to take is place. Thus, a steady stream of parts isprovided.

In a preferred embodiment of the present invention, a containerunloading system is provided which includes a two-tiered rail systemthat has been adapted to include an upper set of feed rails and a lowerset of return rails that cycle carts carrying loads from the back of thesystem to the front of the system for unloading. At the system's frontend, the feed rails have sections of increased angularity which supportthe load at an angle which increases the accessibility to thecontainer's contents. The sections of increased angularity also increasethe vertical distance between the upper and lower rails which allows thesystem to be used with a wide variety of parts bins and containers.

Once the container is unloaded, cart stops which hold the cart andcontainer on the angled rails are released and the cart and containerengage a set of transfer ramps which allow the cart to move from rollingengagement with the feed rails to rolling engagement with the lower setof return rails where the cart and container then move to the back ofthe system into a position for reloading.

Because the system is also designed to be used with loads which mayweigh several thousand pounds, another embodiment of the inventionincludes a cart equipped with a speed reducer to retard the cart'sacceleration down the inclined surface. The speed reducer is preferablya brake roller of the type described in U.S. Pat. No. 3,918,561, but amechanical escapement, hydraulic shock absorber or other types of speedgoverning devices which would be readily understood by those of ordinaryskill in the art may also be used.

In another embodiment of the invention, the system uses a speed reducerthat is not attached to the cart. In this embodiment, a similartwo-tiered ramp structure is used to cycle carts and containers. In thisembodiment, as the cart begins its descent down the sections ofincreased angularity, it engages a speed reducer that controls thecart's rate of descent.

Accordingly, an object of the present invention is to provide acontainer unloading system which improves the efficiency of an assemblyline by providing a steady stream of parts to the line worker.

Another object of the present invention is to provide a containerunloading system where the cart and container are held at an anglegreater than the feed rails during unloading so as to improve the lineworker's access to the container's contents.

Another object of the present invention is to provide a containerunloading system having a sufficient vertical distance between the upperand lower rails which allows the system to be used with a vide varietyof parts bins and containers.

An additional object of the present invention is to provide a containerunloading system that uses a speed reducer to control a loadedcontainer's and cart's descent down the sections of increasedangularity.

Still a further object of the present invention is to provide acontainer unloading system that does not interfere with the rollingrelationship and/or lateral alignment of the containers and carts on theupper feed or lower return pair of rails.

Another object of the present invention is to provide a cart returnsystem that transfers unloaded carts from an unloading end and returnsthem to a reloading end where they may be conveniently stored,repositioned or re-used.

An additional object of the present invention is to provide a cartreturn system that can store loads of multiple depths in a first in,first out inventory basis and transfers unloaded carts for subsequentreloading from a different access aisle.

Yet an additional object of the present invention is to provide acontainer unloading system that can be used in combination with multiplerack systems, and that can be used in conjunction with other types ofstorage systems.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, objects and advantages of the presentinvention will become apparent from the following description anddrawings wherein like reference numerals represent like elements in theseveral views, and in which:

FIG. 1 is a perspective view of the present invention with portionsremoved to reveal aspects of the invention;

FIG. 2 is an exploded perspective view of a cart stop of the presentinvention;

FIG. 3 is a plan view of an embodiment of a cart of the presentinvention;

FIG. 4 is an exploded view of a front wheel and attached spur-gear;

FIG. 5 is an exploded perspective view showing a speed reducer, which islocated on the system's rails, that includes dampers and a biasingmechanism which act together to control the descent of the cart andcontainer;

FIG. 6 is a side view of the left-hand side of the invention showing acontainer and cart being supported at an angle so as to improve theaccessibility to the container's contents, a loaded container and cartheld in place on the feed rails by a first cart stop, and an unloadedcontainer and cart traveling along the return rails to the rear of thesystem and into a loading position;

FIG. 7 is a side view of the left-hand side of the invention showing anunloaded container and cart during transfer to the return rails by thetransfer ramps, a loaded container and cart held in place on the feedrails by a first cart stop, and an unloaded container and cart travelingalong the return rails to the rear of the system and into a loadingposition; and

FIG. 8 is a side view of the left-hand side of the invention showing aloaded container and cart beginning the descent down the sections ofincreased angularity and the spur-gears engaging the racks, an unloadedcontainer and cart traveling along the return rails to the rear of thesystem and into a loading position, and a cart and unloaded container ina loading position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with a preferred embodiment of the present invention, thecontainer unloading system, such as that shown in FIG. 1, consists of atleast one cart 14 and at least one two-tiered rail system 16, whichincludes a pair of spaced, parallel feed rails 18 which have rollingsurfaces 20, webs 22, and guide edges 24. Two-tiered rail system 16 alsohas at least one pair of spaced, parallel return rails 26, which furtherinclude rolling surfaces 28, webs 30, and guide edges 32. As usedherein, and as shown on FIG. 1, front end 10 refers to an unloading endwhich is generally associated with an aisle for line workers (notshown). The rear end 12, as used herein, refers to a loading orreloading end which is also generally associated with an aisle forworkers and equipment used in loading or reloading (not shown). Feedrails 18 are positioned above return rails 26 and are sloped downwardlyfrom the rear end 12 to front end 10 at a gradual angle. Feed rails 18further include sections of increased angularity 34 near front end 10.Return rails 26 are sloped downwardly from front end 10 to rear end 12at a gradual angle.

Rails 18 and 26 are secured in place by upright columns 36 and parallelbeams 38. Extra support can be provided as necessary by using a greaternumber of upright columns, cross and parallel beams as will beunderstood by those of skill in the art. Further strength and rigidityis provided by fastening webs 22 and 30 to upright columns 36.

FIG. 1 shows a left-hand portion (when viewed from the unloading orfront end) of the system and it will be understood by those of ordinaryskill in the art that the right-hand portion of is a mirror image of theleft-hand portion. In addition, although angle members, channels andI-beams are shown for the elements in the preferred embodiments, it willbe understood that other structural members having differentcross-sectional shapes may be employed to practice the inventions.

Feed rails 18 further include notches or first passageways 40, which areconnected to transfer ramps 42 containing ramp hinges 44 and curvedportions 46. Opposingly located across from transfer ramps 42 are hingeddampeners 48. Hinged dampeners 48 are biased toward transfer ramps 42 byspring bolts 50. Although the use of transfer ramps and dampeners is notrequired, their use is desirable to facilitate the smooth transfer ofcart 14 and to prevent any needless damage to the cart and wheels.

Notches 40 are depth-proportioned to permit a pair of front wheels 52 ofcart 14 to roll forward on rolling surfaces 20 of feed rails 18, pastand unobstructed by notches 40. The distance between the front mostportion of sections 34 and notches 40 should be equal to or slightlyless than the distance between front wheels 52 and rear wheels 54 ofcart 14. In this manner, cart 14 is transferred from feed rails 18 toreturn rails 26 by moving from rolling engagement with feed rails 18 torolling engagement with return rails 26.

As shown in FIGS. 1 and 2, the system further includes a first set ofcart stops 56 having rotatable rods 58 and rod brackets 60 which areattached to webs 22 of feed rails 18. Stops 56 are positioned to preventfront wheels 52 from proceeding past notches 40 and onto sections ofincreased angularity 34 when in the engaged position. Second set of cartstops 62, which may be of the same construction as stops 56, includerods 64, brackets 66 and are attached at webs 30 of return rails 26.Second set of cart stops 62 engage front wheels 52 and prevent thetransfer of cart 14 from feed rails 18 to return rails 26 when in theengaged position.

Feed rails 18 terminate at a point above rolling surfaces 28 of returnrails 26 so as to form apertures or second passageways 68. The height ofapertures 68 should be slightly larger that the diameter of front wheels52 so as to allow for the passage of front wheels 52 through apertures68 and under sections 34 thereby permitting the return of the carts.

The details of cart 14 may better be seen with reference to FIG. 3. Theframe of cart 14 consists of side angle members 70, front member 72,rear member 74 and any additional number of cross members 76 that may benecessary to support a given load. Side members 70 are secured tomembers 72, 74 and 76, which together form the load bearing surface ofcart 14 and can be adapted to carry unit load container 77 as shown inFIG. 1.

As indicated, cart 14 includes a pair of front wheels 52 and a pair ofrear wheels 54. Wheels 52 and 54 are rotatably mounted to cart 14 andfront wheels 52 extend laterally outside the width of cart 14 a distancegreater than rear wheels 54 an amount sufficient for front wheels 52 toroll forward on rolling surfaces 20 of feed rails 18 withoutinterference from or passing through notches 40.

Rear wheels 54 are rotatably mounted to side channels 70 and are spacedsuch that when rear wheels 54 are in rolling engagement with upperrolling surfaces 20, they will intersect notches 40, when desired. Cart14 may be further provided with a pair of front guide wheels 78 and apair of rear guide wheels 80 (see FIG. 3). Front guide wheels 78 andrear guide wheels 80 are positioned to cooperate with guide edges 24 and32, thereby keeping cart 14 in proper lateral alignment and providingsmooth operation as cart 14 rolls along rails 18 and 26.

It will be apparent to those of ordinary skill in the art that there areother methods to guide the cart during operation as well. For example,fixed guides (not shown) may be used which may be affixed along thesides of cart 14 or elsewhere, in a location to provide the desiredguiding function. Nylon, teflon or similar pads or strips may beemployed, if desired. Accordingly, the various guide elements describedherein, as well as equivalent means, may be used alone or in combinationto achieve the desired and automatic guide function during transfer andfor proper lateral alignment as cart 14 rides on rails 18 and 26.Although the present invention may be practiced without the use ofguides, guides are generally preferred.

As further shown in FIGS. 3 and 4, a preferred embodiment of cart 14 mayfurther include a speed reducer 82 which controls the rate of descent ofcart 14 down sections of increased angularity 34. A speed reducer isnecessary in applications in which the weight of the loaded containerand cart is of sufficient magnitude that allowing the cart to rollfreely down sections 34 would present a dangerous situation if thecart's acceleration was not controlled in some manner.

Speed reducer 82 is preferably a brake roller of the type described inU.S. Pat. No. 3,918,561, but a mechanical escapement, hydraulicgovernor, hysteresis wheel or any other speed governing devices whichwould be readily understood by those of ordinary skill in the art couldalso be used. Speed reducer 82 may be connected to front wheels 52 byaxle 84 and should only be activated when cart 14 begins its descentdown sections of increased angularity 34 so as not to impede theefficient movement of cart 14 along the gradual inclines rollingsurfaces 20 and 28.

In some applications, the weight of the load may be of such a magnitudethat the speed reducer may be overridden if the load is heavy enough tocause front wheels 52 to slide uncontrollably down the rails. To preventsliding, cart 14 may further include spur-gears 86 which are connectedto axle 84 and which mesh with racks 88 located along the sides ofsections 34 as shown in FIGS. 6-8. The diameter of spur-gears 86 shouldbe less than that of front wheels 52 so as not to interfere with thecart's movement on rolling surfaces 20 and 28. Moreover, spur-gears 86may be connected to axle 84 and front wheels 52 may be independentlyconnected to cart 14 thereby limiting the activation of the speedreducer to instances in which cart 14 is on sections 34. Racks 88 shouldalso be positioned slightly above rolling surfaces 20 in order tocompensate for the decreased diameter of gears 86 and to allow for fullengage without interference from front wheels 52.

It should be understood that sliding could also be prevented by the useof sprockets and chains, the use of abrasive, non-skid surfaces andwheels of suitable material for increasing traction such as rubber, andthrough the use other methods which persons of ordinary skill in the artwould appreciate. Moreover, the invention is not limited to the use of asingle speed reducer which has been attached to the front wheels by anaxle. Other design choices may include the use of multiple speedreducers or the use of a speed reducer which may be attached to thefront and/or rear wheels as well as being an independent axlealtogether.

In another embodiment the descent of cart 14 is controlled by the use ofa speed reducer 90 which is not connected to cart 14. As shown in FIG.5, an embodiment of this design includes hinged dampers 92 which areconnected to rail system 16 by hinges 93. Dampers 92 are also connectedto spring bolts 95 which resist any upward movement of dampers 92 andbias dampers 92 toward feed rails 18. It should also be understood thatother compressible mechanisms such as adjustable hydraulic shockabsorbers or any other compressible mechanical device which would bereadily apparent to those of ordinary skill in the art could also beused in the place of the disclosed spring bolts 95 to either indirectlyor directly engage cart 14. Moreover, those of ordinary skill in the artwould recognize that the cart's descent may also be controlled bydirectly engaging a compressible mechanism such as a spring or hydraulicpiston. Use of a system of this design also eliminates the possibilityof uncontrolled sliding.

The operation of the invention may be better understood by reference toFIGS. 6-8. In a preferred embodiment using spur-gears 86 and racks 88,at least one cart 14 is needed to cycle through the system, although theinvention could easily accommodate a greater number of carts. As shownin FIG. 6, a loaded container 77(A) and cart 14 is at rest on feed rails18. First set of cart stops 56 permit the selective transfer of cartsand prevent any forward movement of cart 14 and container 77(A) alongthe downward slope of feed rails 18 and from rolling down sections ofincreased angularity 34. At the same time, a cart and container 77(B)that is being unloaded may be sitting at an increased angle uponincreased angular sections 34 and any forward movement will be preventedby second set of cart stops 62. An additional cart 14 and container77(C) is returning to a loading position at rear end 12.

Once the container is emptied, an operator disengages cart stops 62.Upon disengagement, spur-gears 86 will move forward along racks 88 untilcart 14 and container 77(B) fall off of feed rails 18 and onto rollingsurfaces 28 of return rails 26 as shown in FIG. 7. At the same time,rear wheels 54 will also move forward until intersecting notches 40 andengaging transfer ramps 42 and dampeners 48.

Dampeners 48 are biased towards transfer ramps 42 by spring bolts 50 orhydraulic shock absorbers (not shown) and slow the rate of descent ofrear wheels 54 down transfer ramps 42 to prevent any needless damage.Upon reaching curved portions 46, the downward inclines of rollingsurfaces 28 and curves 46 propel cart 14 rearward along return rails 26until cart 14 and container 77(B) come to rest in a position forreloading. As cart 14 is moving rearward, front wheels 52 will passbeneath front sections 34 by traveling through apertures 68 and will notbe obstructed by curved portion 46 since hinges 44 allow this segment toswing up upon passage of the cart. As shown in FIG. 8, once unloadedcontainer 77(B) and cart 14 clear increased angular sections 34, firstset of cart stops 56 may be disengaged as desired. This causes anotherloaded container 77(A) and cart 14 to move forward on rolling surfaces20 until cart 14 and container 77(A) reach increased angular sections34. Upon reaching sections 34, spur-gears 86 will engage racks 88 andspeed reducer 82 will cause cart 14 and container 77(A) to ride safelyon racks 88 until transfer to return rails 26 where, once again, cart 14and container 77(A) will ride on front wheels 52. In this fashion, afresh load of parts will be delivered for unloading and the cycle willcontinue.

In an embodiment in which compressible speed reducer 90 is used, theoverall operation of the invention is not changed. However, as cart 14begins its descent down sections 34, front wheels 52 of cart 14 engagedampers 92. As the wheels 52 push dampers 92 upwardly, spring bolts 95will be compressed and resist the upward movement of dampers 92. Throughthe cart's engagement with dampers 92, the resistance generated fromspring bolts 95 indirectly provides the necessary control of cart 14. Toprovide a system that can be adjusted to control carts of differentweight, an adjustable compressible mechanism may be used. In this typeof system, as the weight of the carts is increased, the amount oftension provided can be increased as well.

In an embodiment of this design there may be no need to use spur-gears86 and racks 88 since compressible speed reducer 90 maintains control ofcart 14 for its entire descent down sections 34 until transfer to rails26. Speed reducer 90 should also be designed so as not to interfere withthe transfer of cart 14 from feed rails 18 to return rails 26.

While the preferred embodiments of the present invention have beenillustrated and described, it will be understood by those of ordinaryskill in the art that changes and other modifications can be madewithout departing from the invention in its broader aspects.

Accordingly, persons of ordinary skill in the art would also understandthat the invention would not be limited to the containers used and thatcart 14 could be adapted for use with slip-sheets, containers, barrels,parts bins and other types of unit loads used in manufacturing orwarehouse systems. Various features of the present invention are setforth in the following claims.

What is claimed is:
 1. A container unloading system having an unloadingfront end and loading rear end comprising:a two-tiered rail systemhaving a set of parallel feed rails and a set of parallel return railspositioned below said feed rails; said feed rails having sections ofincreased angularity near said front end; at least one cart having aload bearing surface adapted to carry a unit load and further includingsupport means for the attachment of front and rear wheels; said wheelspositioned on said cart for rolling engagement with said feed rails andsaid return rails of said two-tiered rail system; a first set ofpassageways located above said return rails, said first passagewaysadapted to permit said rear wheels of said cart to move from rollingengagement with said feed rails to rolling engagement with said returnrails; a second set of passageways located above said return rails, saidsecond passageways adapted to permit said front wheels of said cart tomove from rolling engagement with said feed rails to rolling engagementwith said return rails; said cart selectively retained on said feedrails during the unloading of said cart; said rail system adapted forsaid cart to be supported on said sections of increased angularityduring the unloading of said unit load; and a speed reduction means forcontrolling said cart's descent down said sections of increasedangularity.
 2. The device of claim 1 further including a set of transferramps adjacently located near said first passageways which engage saidrear wheels and facilitate the transfer of said cart from rollingengagement with said feed rails to rolling engagement with said returnrails.
 3. The device of claim 2 further including dampeners opposinglylocated from said transfer ramps for controlling the descent of saidcart down said transfer ramps.
 4. The device of claim 1 wherein saidspeed reduction means is attached to said cart and is selected from thegroup consisting of a brake roller, hysteresis wheel, mechanicalescapement, or hydraulic governor.
 5. The device of claim 4 wherein saidcart further includes an axle connected to said speed reducer and saidaxle having at its ends spur-gears for engaging racks located alongsidesaid sections of increased angularity.
 6. The device of claim 4 whereinsaid cart further includes an axle connected to said speed reducer andsaid axle having at its ends sprockets for engaging chains locatedalongside said sections of increased angularity.
 7. The device of claim1 wherein said speed reduction means is a compressible mechanism whichis attached to said rail system and engages said cart.